29,022 research outputs found
Midcourse navigation using statistical filter theory, a manual theodolite, and symbolic computer control
Midcourse navigation using statistical filter theory, manual theodolite, and symbolic computer control applied to manned spacecraf
The concept of social pharmacy
The 13th International Social Pharmacy Workshop will be held in Malta in July 2004. The Social Pharmacy Workshops are international conferences for research in social and behavioural pharmacy. Meetings are held every second year and participation has grown steadily since the first Workshop was held in Helsinki, Finland, in 1980. Following the successful 2002 conference in Sydney, Australia, the 2004 meeting in Malta will be the first one held in the Mediterranean area!peer-reviewe
Stellar Oscillations Network Group
Stellar Oscillations Network Group (SONG) is an initiative aimed at designing
and building a network of 1m-class telescopes dedicated to asteroseismology and
planet hunting. SONG will have 8 identical telescope nodes each equipped with a
high-resolution spectrograph and an iodine cell for obtaining precision radial
velocities and a CCD camera for guiding and imaging purposes. The main
asteroseismology targets for the network are the brightest (V<6) stars. In
order to improve performance and reduce maintenance costs the instrumentation
will only have very few modes of operation. In this contribution we describe
the motivations for establishing a network, the basic outline of SONG and the
expected performance.Comment: Proc. Vienna Workshop on the Future of Asteroseismology, 20 - 22
September 2006. Comm. in Asteroseismology, Vol. 150, in the pres
Generation and detection of a sub-Poissonian atom number distribution in a one-dimensional optical lattice
We demonstrate preparation and detection of an atom number distribution in a
one-dimensional atomic lattice with the variance dB below the Poissonian
noise level. A mesoscopic ensemble containing a few thousand atoms is trapped
in the evanescent field of a nanofiber. The atom number is measured through
dual-color homodyne interferometry with a pW-power shot noise limited probe.
Strong coupling of the evanescent probe guided by the nanofiber allows for a
real-time measurement with a precision of atoms on an ensemble of some
atoms in a one-dimensional trap. The method is very well suited for
generating collective atomic entangled or spin-squeezed states via a quantum
non-demolition measurement as well as for tomography of exotic atomic states in
a one-dimensional lattice
Ultraviolet downconverting phosphor for use with silicon CCD imagers
The properties and application of a UV downconverting phosphor (coronene) to silicon charge coupled devices are discussed. Measurements of the absorption spectrum have been extended to below 1000 A, and preliminary results indicate the existence of useful response to at least 584 A. The average conversion efficiency of coronene was measured to be ~20% at 2537 A. Imagery at 3650 A using a backside illuminated 800 X 800 CCD coated with coronene is presented
Numerical indications on the semiclassical limit of the flipped vertex
We introduce a technique for testing the semiclassical limit of a quantum
gravity vertex amplitude. The technique is based on the propagation of a
semiclassical wave packet. We apply this technique to the newly introduced
"flipped" vertex in loop quantum gravity, in order to test the intertwiner
dependence of the vertex. Under some drastic simplifications, we find very
preliminary, but surprisingly good numerical evidence for the correct classical
limit.Comment: 4 pages, 8 figure
MCMC Exploration of Supermassive Black Hole Binary Inspirals
The Laser Interferometer Space Antenna will be able to detect the inspiral
and merger of Super Massive Black Hole Binaries (SMBHBs) anywhere in the
Universe. Standard matched filtering techniques can be used to detect and
characterize these systems. Markov Chain Monte Carlo (MCMC) methods are ideally
suited to this and other LISA data analysis problems as they are able to
efficiently handle models with large dimensions. Here we compare the posterior
parameter distributions derived by an MCMC algorithm with the distributions
predicted by the Fisher information matrix. We find excellent agreement for the
extrinsic parameters, while the Fisher matrix slightly overestimates errors in
the intrinsic parameters.Comment: Submitted to CQG as a GWDAW-10 Conference Proceedings, 9 pages, 5
figures, Published Versio
Modeling temporal fluctuations in avalanching systems
We demonstrate how to model the toppling activity in avalanching systems by
stochastic differential equations (SDEs). The theory is developed as a
generalization of the classical mean field approach to sandpile dynamics by
formulating it as a generalization of Itoh's SDE. This equation contains a
fractional Gaussian noise term representing the branching of an avalanche into
small active clusters, and a drift term reflecting the tendency for small
avalanches to grow and large avalanches to be constricted by the finite system
size. If one defines avalanching to take place when the toppling activity
exceeds a certain threshold the stochastic model allows us to compute the
avalanche exponents in the continum limit as functions of the Hurst exponent of
the noise. The results are found to agree well with numerical simulations in
the Bak-Tang-Wiesenfeld and Zhang sandpile models. The stochastic model also
provides a method for computing the probability density functions of the
fluctuations in the toppling activity itself. We show that the sandpiles do not
belong to the class of phenomena giving rise to universal non-Gaussian
probability density functions for the global activity. Moreover, we demonstrate
essential differences between the fluctuations of total kinetic energy in a
two-dimensional turbulence simulation and the toppling activity in sandpiles.Comment: 14 pages, 11 figure
ASTEC -- the Aarhus STellar Evolution Code
The Aarhus code is the result of a long development, starting in 1974, and
still ongoing. A novel feature is the integration of the computation of
adiabatic oscillations for specified models as part of the code. It offers
substantial flexibility in terms of microphysics and has been carefully tested
for the computation of solar models. However, considerable development is still
required in the treatment of nuclear reactions, diffusion and convective
mixing.Comment: Astrophys. Space Sci, in the pres
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